1,3,7-trimethylxanthine is the chemical name for caffeine: a stimulant drug. Specifically, it stimulates the bulbar respiratory centre in the brain.

It stimulates gastric secretions and muscle striates, it is a spasmolytic and vasodialator, antagonizes benzodiazepines and acts as a diuretic, as well as facilitating increased work and decreased somnolence.

It works by increasing cellular concentration of cyclic AMP (Adenosine Mono Phosphate) and inhibiting phosphdiesterase; it increases neuron firing by increasing calcium entry during action potentials.

It is metabolized by CYP1A2. It can be administered intravenously and gastically, with a plasmatic rate of absorption of 1 hour and a 4 hour half life.

Less technically, caffeine contributes to the deliciousness and addictiveness of such things as coffee, chocolate, and Coca Cola.